Initialization by FE solution: operation

Starting by FE solution

It is possible to start a transient computation by using as initial state the result of a Magneto Static, an AC Steady-State Magnetic or a Transient Magnetic problem.

AC Steady-State - Transient Magnetic relevance / example

The AC Steady-State application permits the study of the steady state regime, but it has the following drawbacks:

• approximations in the taking into consideration of the magnetic saturation*
• no possibility to compute the harmonics in space and time

The Transient Magnetic application compensates for the limits quoted above, but it has the drawback of requiring a computation time that can be quite long. Then, the number of time steps is important.

Starting a Transient Magnetic application on the basis of the AC Steady-State solution permits to rapidly reach the steady state regime without being forced to solve all the time steps of the Transient Magnetic problem until the steady state regime is reached.

Transient Magnetic - Transient Magnetic relevance / example

As with an AC Steady-State application, the Transient Magnetic application permits to obtain the steady state regime more rapidly without the need for the user to make again the computation of the transient phases or those for start-up (starting up of a synchronous machine with magnets, for instance).

It also permits to reach a certain specified point of the steady state regime – for example the passage at zero of the current of one of the phases of an electric alternator.

Finally, and mainly, it gives the possibility of an initialization by FE problem when the system comprises permanent magnets, which is not possible with an initialization by an AC Steady-State problem.

Operation

The operation principle is described in the table below in the case of an AC Steady-State – Transient Magnetic sequence.